Catalytic cracking of residuum oils containing metal contaminants in several stages



United States Patent 3,303,123 CATALYTIC CRACKING 0F RESIDUUM OILS CONTAINING METAL CONTAMINANTS IN SEVERAL STAGES Edwin M. Payton, Borger, and James W.'Slover, Phillips,

Tex., assignors to Phillips Petroleum Company, a corporation of Delaware Filed Oct. 116, 1964, Ser. No. 404,335

6 Claims. (Cl. 20876) This invention relates to catalytic conversion of reactant materials such as hydrocarbons. In one aspect it relates to a method and means for catalytic conversion of hydrocarbons of differing properties at different conditions in a unitary process and apparatus. In one of its more specific aspects it relates to a method and means for the simultaneous and separate catalytic cracking of a hydrocarbon residuum such as topped crude and an aromatic hydrocarbon'such as the extract obtained by solvent extraction of the cycle oils resulting from such cracking operation. H

It is known to crackhydrocarbon fluids catalytically to increase the quantity and quality of the gasoline or motor fuel product. In such operations a refractory heavy product is produced, for which there is little demand, and therefore this heavy product is usually returned to the cracking operation. It has been proposed to solvent extractthis heavy recycleoil so as to remove therefrom aromatic hydrocarbons which are carbon formers and gas formers and to recycle the raflinate from this solvent extractionstep to the cracking operation.

lytic cracking zones, wherein feed stocks containing different concentrations of contaminating metals are separately cracked, to solvent extract the heavier oil from the cracking zone that treats the feed stock containing the least amount of contaminants, to pass the raflinate to the cracking zone wherein the feed stock contains a greater amount of contaminants and to pass the extract oil to a carbon black process. Such process increases the aromatic or extract oil production. The extract from the solvent extraction step constitutes a preferred feed stock for the manufacture of carbon black'by the furnace process and a considerable quantity of such extract is consumed in the carbon black process.

In the catalytic cracking of hydrocarbons wherein more than one catalytic cracking zone is employed, it is usually considered desirable to crack residual hydrocarbons, such as topped crude, pitch, and/ or other hydrocarbon fluids containing relatively large amounts of metal compound contaminants or other cokeand gas-forming components, in a reaction zone employing catalyst which has been discarded from a catalytic cracking zone wherein distillate hydrocarbons, such as gas oils and recycle oils from the catalytic cracking process which contain relatively small amounts of metal compound contaminants or cokeand gas-forming components, are contacted with a fresh or relatively little-used catalyst. The distillate hydrocarbons are generally more refractory than the residual hydrocarbons and therefore these distillate hydrocarbons are usually catalytically cracked at a higher temperature than are the residual hydrocarbons. The raflinate from the solvent extraction step is usually added as a recycle stream to the catalytic cracking zone wherein distillates are cracked.

The solvent extraction of the heavy cycle oils in the catalytic cracking of hydrocarbons has resulted in the production of extract stocks which are sometimes in excess of the requirements of the carbon black process; however, solvent extracting the cycle oils has so improved these cycle oils in the form of raflinate for the catalytic cracking process that the solvent extraction of these cycle oils is continued even though an excess of extraction has resulted. The excess of extract oil has been added to the catalytic cracking zone wherein distillates are cracked because the extract is quite refractory and requires crack ing temperatures higher than those that are tolerated by the residual oils that are cracked in the cracking zone utilizing the used catalyst. When extract oils are added to .the distillate foils the clean. catalyst cracking zone, it is necessary to increase .the cracking temperature and .thus operate at a compromise temperature between the optimum cracking temperature for the distillate oils and the optimum cracking temperature for the extract oils. In this operation the cycle oils will contain an abnormally large concentration of aromatics.

, It is an object of this invention to provide a method .for cracking an extract oil in a catalytic cracking process such that the distillate oil charge, the residual oil charge,

and the extract oil charge canieach be catalytically cracked.

at its optimum cracking temperature. Another object of this invention is to provide a method for the economic disposal of excess extract oils. Still another object of this invention is to providea method for cracking an.extract oil in a catalytic cracking process so as to provide a minimum concentration of aromatic components in the cycle oils removed from the distillate oil cracking zone.-. Other and further objects and advantages of the invention will be apparent to one skilledin the art upon study of this disclosure includingthe drawingand the detailed descrip- It has-also been proposed to employ two or more catation of the invention, p

The drawing is'a diagrammatic flow plan of a preferred embodiment of the invention. V i V a According to the method of the. invention, the extract oil is contacted with catalyst in a separate riser in the residual oil cracking zone at a catalyst-to-oil ratio sufficient to crack the extract oil at optimum cracking temperature which is considerably higher than that of the residual oil. The extract oil can be catalytically cracked in a separate riser in the distillate oil cracking zone; however, this is less preferred because of the inherent increase in concentration of aromatic components in the cycle oils removed from this catalytic cracking zone. It is a feature of the invention that make-up catalyst passed from the distillate oil cracking zone to the residual oil cracking zone can be employed as the catalyst for cracking the extract oil and thus the extract oil can be cracked with clean catalyst in the dirty catalyst cracking zone. The residual oils are usually catalytically cracked at a temperature of about 870-940 F. and the distillate oils, being more refractory, are usually catalytically cracked at a temperature of about 890980 F. The extract oils being considerably more refractory than the other charge stocks are advantageously catalytically cracked at a temperature of about 950-1050 F. The addition of liquid water to the extract oil prior to contacting the oil with hot catalyst aids in conversion of the extract oil. The water addition permits an increase in the catalyst-to-oil ratio.

Referring now to the drawing, a residual oil such as topped crude enters the system via conduit 10 and then is passed into risers 11 and 12 along with liquid Water from conduit 13. The mixture of topped crude and water then passes into catalytic cracker 14 which is composed of a regeneration chamber 15 and a superimposed reactor 16. This can be referred to as an over-and-under catalytic cracker. The risers 11 and 12 terminate in the reactor 16 above the level of a fluidized bed of catalyst contained therein. A disengaging and stripping section in the lower portion of reactor 16 passes used catalyst from the reactor section downwardly into the regenerator section 15. Air is admitted to the lower portion of regenerator 15 via conduit 17 and a fluidizing gas is admitted to the bottom portion of regenerator 15 via conduit 18. The stream of topped crude entrains catalyst from the regenerator and a mixture of topped crude and catalyst passes upwardly through the risers and is discharged into the reactor section 16. Combustion gases resulting from regenerating catalyst are removed from regenerator 15 via conduit 19. The vaporized effiuent from reactor 16 is removed via conduit 21 and passed'to fractionation zone 22 wherein the effluent products'are separated into fractions having difierent boiling ranges from whence C and lighter materialsare remove-d via conduit 23, a gasoline cut is removed via conduit 24 and light cycle oil is removed via conduit 25 to form these various products of the process. Heavy cycle oil removed via conduit 26 and decant oil removed via conduit 27 are passed to a'solvent extraction plant 28.

A second hydrocarbon stream comprising a distillate such asgas oil is charged to a second catalytic cracker 30 via conduit 29. Reactor 30 with its attendant regenerator 31 is illustrated as. a side-by-side catalytic cracker as distinguished from the over-and-un-der catalytic cracker 14. Regenerated catalyst from regenerator 31 is passed via conduit 32 into'conduit' 29 so that a mixture of oil and catalyst passes upwardly through riser 33 into reactor 30 wherein a fluidized bed of solid catalyst is maintained. Catalyst isremoved from reactor 30 via conduit 34 and is passed along with a conveying stream of air through conduit 35 into regenerator 31. Combustion Vaporized effluent passes from reactor 30 via conduit 37 to a s'econd fractionation zone 38. C and lighter hydrocarbons removed via conduit 41, a gasoline fraction removed via conduit 42 and a light cycle oil removed via conduit 43 are recovered as products of the process. Heavy cycle oil removed via conduit 44. and decant oil removed via conduit 45 are passed via conduit 46 to the solvent extraction zone 28 along with the oil in conduit 27. v A slurry of catalyst fines and fractionator tower bottoms from fractionation zone 38 is passed via conduit gases are removed from regenerator 31 via conduit 36. p

39 along with a similar slurry of catalyst fines and 'fractionator tower bottoms from fractionator zone 22 in conduit 47 to conduit 29 as a portion of the feed to catalytic cracker reactor 30. If desired, a portion of the heavy cycle oil in conduit 44 can be passed via conduit 48 to conduit 29. The rafiinate fromsolvent extraction zone 28 is passed via conduit 49 to conduit 29.

Extract oil from solvent extraction zone 28 is removed via conduit 51. Excess extract oil 'over that removed as product is passed via conduit 52 to riser 54 in over-andunder catalytic cracker 14. Hot regenerated catalyst from regenerator 31 is passed via conduit 55 and admixed with the extract oil and steam in. riser 54. Liquid water is passed via conduit 13 and conduit 56 into contact with the extract oil in conduit. 52 before it is. contacted with catalyst in riser 54. I

Conventional cracking catalysts suchas synthetic or natural clays, bauxite, brucite, silica-alumina, and the like can be used in the practice'of the invention. Conventionalreaction conditions of temperature, pressure, space velocity and the like are applicable in' the practice of the invention.

The following example may be helpful in attaining a clear understanding of the invention but should not be construed as limiting the claims unduly.

' EXAMPLE i 4 In the following tables the following abbreviations are employed:

BMCI==Bureau of Mines Correlation Index b./d.=Barrels per day lb./hr. =Poun-ds per hour LV percent=Liquid volume percent Wt. ratio=Weight ratio Table I COMPARISON OF CRACKING EXTRACT SEPARATELY AND MIXED WITH TOPPED CRUDE Run 1 Run 2 Risers 11, Risers Riser 54 12 and 54 V 11 and 12 Extract, b/d 2, 600 2, 600 A131 at 60 F 10 BMCI Temp. of Feed, F. 365 1110 added, b.lhr *32 .12 Steam, lh./hr *11, 000 5, 000 Catalyst/oil wt. rat *1311 23:1 Riser Outlet, F.. 960 990 Conversion, LV

percent Topued Crude, b./d API at 60 F Temp; of Feed, F I H2O added, b./hr

Steam, lb Catalyst/oilwt rati s Riser Outlet, F g O0 1V6l'Sl011, LV

percent s. #57

*Value for the mixture of extract and topped crude.

Table II.

Table II P ROD UCTION Run 1 Run 2 Run 3 Topped Crude, b./d; .r 20, 000 20,000 21, 915 Extract, b./d 2, 600 2, 600 2, 845

Total Charge, b./d 22, 600 22.600 24, 760 Conversion, b./d 12, S60 12, 860 14, 090 Conversion, LV percent 57 57 57 Gasoline, bJd 9, 9, 432 10, 330 Coke, 111/111; as, 100 34, 770 38,100

Comparison of Runs 1 and 2 shows that'by operating according to the invention (Run 2) gasoline production is increased 300 barrels per day and coke production is reduced about 80,000 pounds per day at the same conver- The unit is limited to producing 38,100 pounds of coke per hour because this is the maximum amount of coke that can be burned in the regeneration step without, raising the temperature of the regenerated catalyst to a value higher than can be tolerated in the cracking operation. Thus it can be seen that practice of the invention as in Run 2 reduces coke production so that the total charge to the unit can be increased as shown in Run 3 so that gasoline production is increased to 10,330

barrels per day at maximum coke production. This means that gasoline production can be increased by 1200 barrels per day in this unit by practice of the invention.

That which is claimed is:

1. In the catalytic cracking of hydrocarbons wherein residuum containing a relatively large amount of metal contaminants is charged to a first catalytic cracking zone admixed with hot, regenerated, dirty catalyst at a catalyst-to-oil ratio sufiicient to raise the temperature of the residuum charge to about 870 to 940 F., distillate oils containing a relatively small amount of metal contaminants are charged to a second catalytic cracking zone admixed with hot, regenerated, clean catalyst at a catalystto-oil ratio sutficient to raise the temperature of the dis tillate oils to about 890 to 980 F., cycle oils are solvent extracted, and the raflinate from the solvent extraction step are charged to the second catalytic cracking zone as a portion of the distillate oil charge, the improvement comprising charging extract from said solvent extraction step to said first catalytic cracking zone in a separate zone within said first zone admixed with hot, regenerated catalyst at a catalyst-to-oil ratio suflicient to raise the temperature of the extract charge to about 950 to 1050 F.

2. The process of claim 1 wherein liquid water in the amount of about 1 to pounds of water per barrel of extract is added to the extract charge before the catalyst is admixed with the extract.

3. The process of claim 1 wherein the catalyst admixed with the extract oil is clean catalyst from said second cracking zone.

4. The process of claim 1 wherein the catalyst admixed with the extract oil is dirty catalyst from said first cracking zone.

5. In the catalytic cracking of hydrocarbons wherein the hydrocarbon charge to a reaction zone is admixed with hot, regenerated catalyst at a catalyst-to-oil ratio suflicient to raise the temperature of the hydrocarbon charge to a predetermined level, the catalyst-to-oil ratio of the residuum charge in a first reaction zone is sufiicient to raise the residuum charge to a temperature in the range of about 870 to 940 F., and the catalyst-to-oil ratio of the distillate charge in a second reaction zone is sufiicient to raise the distillate charge to a temperature in the range of about 890 to 980 F., the improvement comprising charging an extract from a solvent extraction step and hot, regenerated catalyst to a third reaction zone within said first reaction zone at a catalyst-to-oil ratio suflicient to raise the temperature of the extract charge in said third reaction zone to the range of about 950 to 1050" F.

6. In the catalytic cracking of hydrocarbons wherein residuum is charged to a first catalytic cracking zone at a temperature of about 935 F., distillate oils are charged to a second catalytic cracking zone at a temperature of about 950 F., cycle oils are solvent extracted and the rafiinate from the solvent extraction step is charged to said second catalytic cracking zone at a temperature of about 950 F., the improvement comprising charging extract from said solvent extraction step to a third catalytic cracking zone within said first zone at a temperature of about 990 F.

References Cited by the Examiner UNITED STATES PATENTS 2,461,958 2/ 1949 Bonnell 20874 2,902,443 9/ 1959 Wadley 20896 3,053,752 9/ 1962 Swanson 208164 3,164,542. 1/ 1965 Mitchell 20896 DELBERT E. GANTZ, Primary Examiner.

ABRAHAM RIMENS, Examiner. 

1. IN THE CATALYTIC CRACKING OF HYDROCARBON WHEREIN RESIDUUM CONTAINING A RELATIVELY LARGE AMOUNT OF METAL CONTAMINANTS IS CHARGED TO A FIRST CATALYTIC CRACKING ZONE ADMIXED WITH HOT, REGENERATED, DIRTY CATALYST AT A CATALYST-TO-OIL RATIO SUFFICIENT TO RAISE THE TEMPERATURE OF HE RESIDUUM CHARGE TO ABOUT 870 TO 940*F., DISTILLATE OILS CONTAINING A RELATIVELY SMALL AMOUNT OF METAL CONTAMINANTS ARE CHARGED TO A SECOND CATALYTIC CRACKING ZONE ADMIXED WITH HOT, REGENERATED, CLEAN CATALYST AT A CATALYSTTO-OIL RATIO SUFFICIENT TO RAISE THE TEMPERATURE OF THE DISTILLATE OILS TO ABOUT 890 TO 980*F., CYCLE OILS ARE SOLVENT EXTRACTED, AND THE RAFFINATE FROM THE SOLVENT EXTRACTION STEP ARE CHARGED TO THE SECOND CATALYTIC CRACKING ZONE AS A PORTION OF THE DISTIALLATE OIL CHARGE, THE IMPROVEMENT COMPRISING CHARGING EXTRACT FROM SAID SOLVENT EXTRACTION STEP TO SAID FIRST CATALYTIC CRACKING ZONE IN A SEPARATE ZONE WITHIN SAID FIRST ZONE ADMIXED WITH HOT, REGENERATED CATALYST AT A CATALYST-TO-OIL RATIO SUFFICIENT TO RAISE THE TEMPERATURE OF THE EXTRACT CHARGE TO ABOUT 950 TO 1050*F. 